The invention relates to a slit alignment ring for use in conjunction with a punch that has a cylindrical shaft and a punch point. The alignment ring can be placed on the shaft and in a defined axial position can be fixed, by elastic deformation by means of a clamping screw spanning the slit, relative to the punch point, in a rotational angle position which is defined by engagement of a pin, fixedly mounted on the punch, with a matching groove in the alignment ring.
The alignment ring has the function of fixing the punch with its punch point in a defined rotational angle position relative to the tool receptacle of the punching machine. It has the further function of keeping the punch in a cassette of the tool magazine. The load-bearing parts of the cassette engage the alignment ring.
In a version that has been customary in the past, the fixation of the rotational angle position of the alignment ring relative to the tool receptacle of the punching machine is effected by means of a key protruding past the surface of the alignment ring and extending radially, which must be made to engage a corresponding groove in the tool receptacle. For fixing the punch relative to the alignment ring, the latter is embodied as a clamping ring that is slit radially on one side. By means of a clamping screw that spans the slit, the slit can be narrowed by elastic deformation of the adjusting ring and at the same time the axial bore of the alignment ring can be reduced in size. In this way, the alignment ring can be firmly clamped on the shaft of the punch in any rotational angle position. However, setting a defined rotational angle position is complicated and inconvenient, especially since auxiliary devices must be used to do so. It has furthermore been found in practice that when there is a load on one side, the connection between the punch and the clamped-on alignment ring, which is made only by friction, is overstressed and yields in the circumferential direction.